Guided flying objects, such as missiles, are generally provided with a transparent dome at their front. Behind this dome, and within the body of the missile, an optical sensing unit is provided for capturing images, and conveying them to a guiding system, which in turn guides the missile to an object or point within the captured images. The dome is generally made of a transparent material which can sustain the aerodynamic and thermal stresses that may be applied on it during the missile flight. In many conventional applications the dome is made of Sapphire.
It is known in the art that the size of the field of regard that can be obtained by the optical sensing unit depends on the spanning angle of the dome used. The term “spanning angle” when used herein refers to the actual angular portion that the dome spans with respect to a full sphere whose spanning angle is 360°. Conventional, prior art domes for missiles are made of at most half a sphere size. Therefore, when a conventional optical sensing unit is provided at the center of dome, and if it is mounted on two-axes gimbals, this optical sensing unit of the prior art can theoretically view a field of regard of at most 180°. Although it is known that the size of the field of regard depends on the spanning angle of the dome, domes spanning more than half a sphere (180°) are generally not in use. This is so, mainly due to technological obstacles in producing Sapphire domes with large spanning angles and with the required characteristics. More particularly, production of a Sapphire dome having a spanning angle substantially larger than 180°, if at all possible, is a very expensive and complicated task.
As said, the maximal active field of operation of a guided missile is limited to within the field of regard. In order to increase the filed of operation of a guided missile, it is therefore necessary to increase its field of regard, which in turn depends on the spanning angle of the dome.
It is an object of the present invention to provide a Sapphire dome having a large spanning angle, larger than 180°.
It is another object of the invention to provide said Sapphire dome with large spanning angle, while maintaining the characteristics required for operation by the missile.
It is still another object of the invention to provide a low cost and simple method for producing a Sapphire dome having a spanning angle larger than 180°.
Other objects and advantages of the present invention will become apparent as the description proceeds.